It is known that alpha and beta hydroxy acids exert beneficial effects on the skin over and above their traditional use to treat acne vulgaris. It is generally believed that the beneficial effects attributed to hydroxy acids are due to their mildly acidic nature, which causes gentle exfoliation of the skin to improve skin clarity, color, and tone, and reduce the appearance of wrinkles and fine lines. Certain sensitive individuals find that hydroxy acids cause skin irritation and dryness. Often, such individuals can overcome the sensitivity to one hydroxy acid by switching to another hydroxy acid. In general, the acidity of a hydroxy acid will depend upon the placement of the hydroxyl and carboxylic acid groups. For example, in glycolic acid the hydroxyl group is found on the alpha carbon atom. In salicylic acid, the hydroxyl group is found on the beta, or number 2, carbon atom. Thus glycolic acid tends to be more acidic (hence more irritating) then salicylic acid because the hydroxyl and carboxylic acid groups are closer to each other on the molecule. In addition, the acidity of a hydroxy compound also tends to depend on the number of hydroxyl groups present, i.e. a compound with more hydroxyl groups tends to be more acidic. Ideally, a hydroxy acid will provide mild exfoliation and other beneficial effects to the skin, without causing skin drynesss and irritation.
U.S. Pat. No. 5,573,759 teaches a method for reducing wrinkles and skin atrophy by applying salicylic acid (2-hydroxybenzoic acid) to the skin. The '759 patent teaches that chronic application of salicylic acid-containing compositions to the skin will reduce skin wrinkling and delay the development of new wrinkles. However, because the hydroxyl group of salicylic acid is on the number 2 carbon atom, salicylic acid tends to be more, rather than less, acidic in nature, and irritating for certain individuals with sensitive skin.
U.S. Pat. No. 5,766,613 teaches the use of dihydroxybenzoic acid derivatives to stimulate the process of epidermal renewal in the skin and combat wrinkles, fine lines, blemishes, and acne. The preferred compound is 2,5-dihydroxybenzoic acid. The dihydroxy benzoic acids taught in the '613 patent are even more irritating to skin than salicylic acid because the have an additional hydroxyl group on the gamma carbon atom in addition to the hydroxyl group on the beta carbon atom.
The object of this invention is to provide a method for exfoliating skin and providing beneficial effects such as reducing the appearance of wrinkles and fine lines, and improving skin color, texture, and tone without the undesired effects of skin dryness and irritation.
The object of the invention is to provide a cosmetic composition that improves skin texture, color, clarity, and tone.